ATLANTA — Rep. Wyche Fowler Jr. amassed a strong lead over Hamilton Jordan, White House chief of staff under Jimmy Carter, in the Democratic primary election Tuesday to name a challenger for Republican Sen. Mack Mattingly.

Fowler was polling 51% of the vote, slightly more than the majority he needed to avoid a runoff election against Jordan.

With 87% of the precincts reporting, Fowler led the field of four Democratic candidates with 262,635 votes or 51%, followed by Jordan with 160,427 votes or 31%. State Rep. John Russell, nephew of legendary Georgia Sen. Richard B. Russell, was running a strong third with 84,279 or 17%. Gerald Belsky, a follower of Lyndon H. LaRouche Jr., had 12,290 or 2%.

Two children of civil rights leaders, Martin Luther King III and Ralph David Abernathy III, were on local ballots in Atlanta. King, 29, was seeking a seat on the Fulton County Commission. With 57% of the vote counted, Abernathy, son of the late King's right-hand man, ran neck-and-neck with Democratic State Rep. John Greer, a 30-year veteran of the Legislature.

Allies Fight Close Race

The Democratic congressional race for the seat being vacated by Fowler featured a fierce contest between allies of the civil rights movement, State Sen. Julian Bond and former Atlanta City Councilman John Lewis.

Bond had 29,300 votes--just less than half the total vote with 90% of the precincts reporting; Lewis had 18,932 votes or 33%, and five others divided the rest. But as in the Fowler-Jordan contest, that left Bond close to the majority needed to avoid a runoff with Lewis.

In Colorado, meanwhile, state Sen. Ted Strickland, state Rep. Bob Kirscht and millionaire businessman Steve Shuck were locked in a close race for the GOP nomination for governor. The winner faces Democratic state Treasurer Roy Romer in November for a chance to succeed three-term Democratic Gov. Richard D. Lamm.

The battle to pick a Democratic challenger for Mattingly, who is completing his first term in the Senate, topped the list of statewide and local races on the Georgia ballot.

As election day dawned, Fowler, 45, an urbane and witty Atlanta attorney and former Atlanta City Council president, appeared to hold the upper hand against Jordan.

A weekend poll, conducted by Atlanta television station WAGA-TV among 502 likely Democratic voters, had shown the congressman leading the former White House aide by 15 percentage points, 38% to 23%, but with 31% of the respondents still undecided.

Wants Big Turnout

"If the people of Georgia turn out and vote, we'll win it," Fowler predicted during an eleventh-hour campaign stop in Columbus. "If the turnout is low . . . there'll be a runoff."

The Georgia secretary of state's office, which supervises elections and certifies the results, reported that only one-fourth of the state's 2.5 million registered voters were going to the polls, which would make it the lowest turnout for a primary since 1962.

Oddly enough, a runoff election would give Jordan the edge over Fowler, some political analysts said.

"For starters," Bill Shipp, an Atlanta Constitution political writer said in a recent column, "the runoff has been scheduled Sept. 2, the day after Labor Day. That ensures a poor turnout of voters, and that works to Jordan's advantage.

Paints Fowler as Liberal

"In addition, he is certain to have at his side leaders of the good-old boy network from the Statehouse. And, finally, history will be with him. Primary front-runners in Georgia usually lose out in a runoff to second-place finishers in the first round."

Jordan, 41, the mastermind of Jimmy Carter's brilliant presidential victory in 1976, sought to paint Fowler as the liberal in the Democratic primary contest, charging during one debate that Fowler was "the clear and lonely voice of unions and liberal causes."

At the same time, Jordan portrayed himself as a "good ole boy" and family man with roots in rural Georgia, distancing himself from his image as the "Peck's bad boy" of the Carter White House.

On the campaign trail, he espoused a new-found conservatism and spoke candidly of his much-publicized bout with lymphatic cancer, of which his doctors have pronounced him cured.

Fowler spent much of the campaign defending himself against Jordan's charges and attempting to soften his image in rural and small-town Georgia as the big-city liberal.

'I'm Not an Echo'

He accused Jordan of copying positions of Sam Nunn, the state's popular conservative Democratic senator. "I'm not an echo," Fowler said. "I don't go around saying I'm Sam Nunn one week, Jimmy Carter one week and maybe Mack Mattingly the next week."

The Democratic contest was of significance nationally to the party, which is seeking to regain control of the Senate from the Republicans this year.

Mattingly, who won renomination handily in the GOP primary against three token opponents, captured the seat in a tight race against former Democratic Sen. Herman Talmadge in 1980.

But that contest came as Talmadge was bedeviled by a string of politically devastating incidents during his last term in office, including a divorce, rumors of heavy drinking and a Senate censure for financial improprieties.

"I call Mattingly the 'accidental senator,' " said Loch Johnson, a University of Georgia political scientist. "The Republicans could have won that year with anyone who had two arms, two legs and could talk well on TV."